Continental Masting Synchrony Analysis

Introduction

This analysis examines masting synchrony between North America and Europe using random year effects (δ_yr) from MASTIF model outputs. The δ_yr represents masting intensity after controlling for environmental variables.

Data Preparation

#Data Summary

Dataset overview
Metric Count
Total Ecoregions 60
North America 33
Europe 27
Years 69
Species 269

#1. Temporal Synchrony

##Continental-scale temporal dynamics

Cross-continental correlation: ρ = 0.201 (p = 0.109)

2. Spatial Synchrony (Moran’s I)

2.1 Ecoregion-level Analysis

2.2 Plot-level Analysis

Table 2: Spatial Synchrony Results

Moran’s I statistics at two spatial scales
Scale continent mean_I median_I pct_positive
Ecoregion Europe -0.123 -0.106 33.333
Ecoregion North America 0.110 0.082 65.625
Plot Europe 0.714 0.727 100.000
Plot North America 0.615 0.573 100.000

Figure 2: Spatial synchrony patterns

3. Species-Specific Effects

Figure 3: Species-level synchrony variation

Table 3: Top species by synchrony strength

Species with strongest continental synchrony patterns
species n_years n_ecoregions rho p_value
acerPlatanoi 13 12 0.401 0.176

4. Aggregation Effects

Key Finding: - Mean absolute correlation for individual species: 0.344 - Aggregated correlation (all species): 0.201 - Reduction due to aggregation: 0.143

This demonstrates that species-specific signals cancel out when aggregated.

5. Geographic Patterns

Figure 4: Spatial distribution of masting signals

Conclusions

  1. Continental asynchrony: North American and European masting patterns are largely independent (ρ = 0.201)

  2. Spatial patterns differ:

    • Europe shows spatial dispersion (negative Moran’s I at ecoregion scale)
    • North America shows weak spatial clustering

  3. Species effects dominate: Individual species show strong synchrony patterns (both positive and negative), but these cancel out when aggregated

  4. Scale matters: Plot-level and ecoregion-level analyses reveal different spatial structures

Supplementary Analyses

Distance-Decay Analysis

Figure S1: Distance-decay relationships

Variance Decomposition

Table S1: Species contributing most to overall variance

Top 5 species by variance contribution
continent species pct_variance n
Europe fagusSylvatic 4.33 119
Europe abiesCephalon 3.95 25
Europe prunusSerotina 3.87 2
Europe carpinusBetulus 3.87 52
Europe sorbusAucupari 3.70 60
North America betulaNeoalask 3.31 49
North America abiesGrandis 3.07 57
North America abiesProcera 3.03 225
North America abiesMagnific 2.79 117
North America abiesAmabilis 2.79 176